“I had to gain 40 pounds,” he told Vanity Fair. “That was probably the most physically arduous; you know, I’ve never had that kind of weight on my chest before. It’s something to get used to.”

The actor also found it difficult to drive the cars from the Prohibition-era, when the film is set. “You’ve got to learn how to drive these cars, and become one with them, and they’re not easy cars to drive,” LaBeouf said. “It’s not like you’ve got a clutch and a throttle—it’s totally different; you’ve got pedals that you’ve never seen before. You look down at the floorboard—there are 12 pedals there. You think you’re flying a hover board. These old-school trucks were very difficult to drive.”

Lawless, also starring Jessica Chastain and Tom Hardy, comes out August 29.